Rick DeNatale wrote:
> 
> You have some very nice renderings which seem to be a a fairly low
> altitude, but I can't seem to find a description on your web site of how
> you did it (or just what the altitude is).

Well - the technique is outlined on:

http://www.imagico.de/pov/planets.html

When you use an isosurface for the geometry you are completely free to 
define the height function - you can combine a low detail basis with a 
higher detail region.  To define the areas the boxed pattern is well 
suited (for faster results i also recently used an object pattern when 
the transit region is not visible).  Mapping this to the sphere can be 
done using mapping warps or f_th/f_ph functions.

Most renders on http://www.imagico.de/pov/earth.html are from an 
altitude of about 200-500km.  The ones on 
http://www.imagico.de/pov/earth2.html are about 50-150km.

> Any tips?  I've thought of trying to slice up the whole earth image
> somehow, is this what you did?  My thought is to process the image with
> the convert tool from ImageMagick.

To extract an area from a very large image you need a tool that is able 
to do this without loading the whole image into memory.  The GDAL 
library can do this (specifically the gdal_translate program):

http://www.gdal.org/

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 07 Oct. 2005)
MegaPOV with mechanics simulation: http://megapov.inetart.net/

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